The present invention relates generally to vertical descent rescue apparatus and particularly to a braking device for a vertical descent rescue apparatus that employs a pourable material that applies a braking force when a centrifugal force is applied to the pourable material.
Vertical descent rescue devices are well known in the art. These devices basically comprise some type of seat or belt for supporting a person, the seat or belt being attached to a reel from which a cable may be spooled. In an emergency situation requiring rapid evacuation from a tall building, a person secures himself to the seat/belts and hooks an end of the cable to a sturdy, anchored structure on the building. The person then jumps from the building. As the person descends, a braking mechanism retards the rotation of the cable reel so that the person descends at a safe speed down to the ground.
An example of such a device is described in Dutch Patent 9401422 assigned to Boon Safety CV. This document describes a self-evacuating portable apparatus for use in tall buildings. The apparatus includes a spool containing a line that reels in either direction, together with braking means to limit the line speed. The brakes act upon the line which is made of an aramid material such as TWARON(copyright) and KEVLAR(copyright).
Russian Patent 1430031 describes a rescue appliance for lowering. The appliance has support cups integrated with brake discs plus adjustable emergency brake shoes.
Brazilian Patent 8701130 describes automatic gravity-based rescue equipment. The equipment comprises a system with a reeled belt for descent from high buildings and automatic rewinding of the belt.
Portuguese Patent 77995 describes rescue equipment for people trapped in buildings. The equipment comprises safety belts in a double reel and multiple suspension cable assembly.
Russian Patent 1005798 describes a centrifugal braking mechanism for a load lowering unit. The mechanism includes springs of various strengths.
Russian Authors Certificate SU 1005798 describes a centrifugal braking rescue mechanism with a reel that includes a braking disc placed in a braking drum cavity and provided with braking blocks. The mechanism is provided with springs of various stiffnesses for pressing the braking blocks against the braking disc. As the person being rescued is lowered. The cable end moves down and causes reel rotation. The torque from the reel is transmitted to the centrifugal braking mechanism flywheel through a cam clutch and planetary reducer. The braking blocks, due to the centrifugal force, rise to the reel inner surface, overcome the spring force and press against the braking disc.
Dutch Patent 8004667 describes a building emergency rescue cable reel which is stopped or braked during pay-out of the cable by cable tension at least once every revolution to limit the run-off speed.
German Patent Document 2748904 describes a roping down reel for rescue equipment. The rescue equipment has a brake mechanism which engages or releases brakes by turning a crank handle.
U.S. Pat. No. 4,448,284 describes a rescue device with a centrifugal dynamic brake. Brake pads are centrifugally pressed against a brake drum as a rescue cable spools off a rotating reel.
A disadvantage of prior art systems is that an enormous amount of heat is generated by the braking action during descent. This generation of heat can lead to descent speeds above safety thresholds, or worse, to catastrophic failure of the braking mechanism.
The present invention seeks to provide improved vertical descent rescue apparatus that is safe and reliable, and is unaffected by brake heat generation.
There is thus provided in accordance with a preferred embodiment of the present invention a braking device including a chamber rotatably mounted on an axle. The chamber defining an inner cavity, a disc mounted on the axle in the inner cavity, the disc having opposing, surfaces extending away from the axle, and a pourable material disposed in the inner cavity such that rotation of the chamber imparts a centrifugal force to the material, causing the material to be wedged between an inner surface of the inner cavity and the opposing faces so as to apply a braking force to the disc.
In accordance with a preferred embodiment of the present invention the device also includes a reel mounted about the axle and connected to the chamber, wherein rotation of the reel imparts rotation to the chamber.
Further in accordance with a preferred embodiment of the present invention the reel is connected to the chamber through a gear assembly. Preferably the gear assembly increases rotation of the chamber relative to the reel.
Additionally in accordance with a preferred embodiment of the present invention the device also includes a cable wound around the reel.
In accordance with a preferred embodiment of the present invention the device also includes a support loop secured to an end of the cable.
Further in accordance with a preferred embodiment of the present invention the device also includes an outer housing connected to the axle, the chamber being inside the housing.
Still further in accordance with a preferred embodiment of the present invention at least one handle is attached to an outer surface of the housing.
In accordance with a preferred embodiment of the present invention at least one person-supporting device is attached to an outer surface of the housing.
Further in accordance with a preferred embodiment of the present invention the pourable material may comprise: sand, powdered material, granulated material, or a liquid.
There is also provided in accordance with a preferred embodiment of the present invention a braking device including a chamber rotatably mounted on an axle, the chamber defining an inner cavity, a disc mounted on the axle in the inner cavity, the disc having opposing surfaces extending away from the axle, and a wedge disposed in the inner cavity such that rotation of the chamber imparts a centrifugal force to the material, causing the material to be wedged between an inner surface of the inner cavity and the opposing faces so as to apply a braking force to the disc.
In accordance with a preferred embodiment of the present invention the wedge is lined with a brake pad. Preferably the opposing surfaces are lined with a brake pad.